Various types of light fixtures are known. Traditional light fixtures presently used in a typical office environment comprise a troffer with at least one fluorescent lamp and a lens having prismatic elements for distributing the light. Typical light fixtures may also use parabolic reflectors to provide a desired light distribution. The fluorescent lamp has long been the light source of choice among lighting designers in many commercial applications, particularly for indoor office lighting. A description of such a fluorescent light fixture may be found in U.S. Pat. Nos. 7,229,192 and 7,261,435, the entire contents of both of which are hereby incorporated by reference.
For many years the most common fluorescent lamps for use in indoor lighting have been the linear T5 (⅝ inch diameter), T8 (1 inch diameter), and the T12 (1½ inch diameter). Such bulbs are inefficient and have a relatively short lamp life. Thus, efforts have been made to identify suitable alternative illumination sources for indoor office lighting applications. Light emitting diodes (“LEDs”) have been identified as one alternative to traditional fluorescent bulbs.
An LED typically includes a diode mounted onto a die or chip, where the diode is surrounded by an encapsulant. The die is connected to a power source, which, in turn, transmits power to the diode. An LED used for lighting or illumination converts electrical energy to light in a manner that results in very little radiant energy outside the visible spectrum. Thus, LEDs are extremely efficient, and their efficiency is rapidly improving. For example, the lumen output obtained by 20 LEDs may soon be obtained by 10 LEDs.
Conventional light fixtures that use LEDs as the light source utilize a separate printed circuit board (“PCB”) that is pre-populated with LEDs wired to the PCB. During assembly of the light fixture, the PCB (with LEDs mounted thereon) is then fastened to the light fixture housing using either multiple screws or other suitable fasteners. This process requires that PCBs be ordered in advance and inventoried prior to assembly, which increases the length of the production cycle for each finished light fixture.
Moreover, the use of a separate circuit board that then must be attached to a portion of the light fixture also increases product assembly time and decreases thermal conductivity between the LEDs and the light fixture housing. Because there is decreased thermal contact between the LEDs and the housing of the light fixture, the use of intermediate conductive materials is often required. All of this leads to increased expense and decreased efficiency.
Thus, there is a need for a light fixture that utilizes LEDs as the light source and that is configured so that the LEDs are able to be directly mounted to a portion of the housing of the light fixture.